2SINGH M, GARG M. Retarding Action of Various Chemicals on Setting and Hardening Characteristics of Gypsum Plaster at Different pH[ J ]. Cement and Concrete Research, 1997,27 (6) :947 - 950.
3SINGH N B, PANDEY S P. Effect of Citric Acid on the Hydration of Plaster of Paris[ J ]. Gypsum &Lime, 1990,224:21 -25.